Subclinical inflammation influences the association between vitamin A- and iron status among schoolchildren in Ghana

Background and objective In resource-poor settings, micronutrient deficiencies such as vitamin A deficiency may coexist with iron-deficiency. In this study we assessed the iron and vitamin A status of schoolchildren and the association between vitamin A and iron status. Methods A cross-sectional design using the baseline data of a dietary intervention trial conducted among randomly selected 5-12 years old schoolchildren (n = 224) from 2 rural schools in northern Ghana. Hemoglobin (Hb), serum ferritin (SF) and serum transferrin receptor (sTfR) concentrations were used as measures of iron status. Retinol binding protein (RBP) was used as a measure of vitamin A status. Subclinical inflammation (SCI) was measured using C-reactive protein (CRP) and alpha(1)-acid glycoprotein (AGP) concentrations. We examined the cross-sectional association between vitamin A and iron status biomarkers with multiple linear regressions. Results The proportions of schoolchildren with anemia (WHO criteria), iron-deficiency (ID, SF<15 mu g/l and/orsTfR>8.5mg/l) and iron-deficiency anemia (IDA, concurrent anemia and ID) were 63.8%, 68.3% and 46.4% respectively. Low or marginal vitamin A status (0.70 mu mol/l <= RBP < 1.05 mu mol/l) was present in 48.2% while 37.5% of the schoolchildren had vitamin A deficiency (VAD, RBP < 0.70 mu mol/l). The prevalence of SCI as well as concurrent VAD and ID were 48.7% and 25% respectively. RBP was associated with Hb (beta = 7.2, P = 0.05) but not SF (beta = 20.7, P = 0.33) and sTfR concentration (beta = 12.0, P = 0.63). In the presence of SCI, RBP was not associated with hemoglobin status but a significant positive association was observed among children without SCI. Conclusions The study shows that RBP is significantly associated with Hb concentration but not with SF and sTfR. The observed relationship between RBP and Hb is only significant in the absence of SCI.